The long term aim is to combine basic and applied research so as to apply psychophysical and evoked potential techniques and the results of modern vision research to the mechanisms of visual pathway diseases and to improving diagnostic and monitoring procedures. Specific aims are as follows: (1) Multiple sclerosis and optic neuritis. Use psychophysical and evoked potential measures of spatial discrimination, spatial frequency and orientation bandwidth, and contrast sensitivity to further define organically-caused distortions of spatial vision. Differentiate the contributions of ON and OFF channel abnormality to overall visual loss. Relate these visual abnormalities to findings on the functional organization of central visual pathways in nonhuman primate. Compare different methods for monitoring the progress of visual demyelination. Distinguish between gaze disorder and neural processing disorder as contributors to Snellen acuity loss. (2) Amblyopia. Develop and apply a technique for measuring and monitoring binocular interactions in patients with depressed acuity due to amblyopia and retrobulbar neuritis. (3) Diabetes. Find whether a simple low-contrast test can detect early retinal changes associated with diabetes.